Alternative fuel for internal combustion engine, containing biobutanol

ABSTRACT

The present invention relates to an alternative fuel composition for internal combustion engines comprising: 1˜88% by weight of biobutanol or a mixture of biobutanol and butanol, 3˜75% by weight of paraffinic hydrocarbon solvents, 3˜35% by weight of toluene, and 6˜30 % by weight of xylene, based on the total weight of the composition.

TECHNICAL FIELD

The present invention relates to a fuel composition for internal combustion engines. The present invention provides a fuel composition for internal combustion engines as an alternative fuel which is applicable not only to an engine using gasoline as a fuel but also to a diesel engine.

BACKGROUND ART

As problems of an exhaustion of fossil fuel and an environmental pollution are getting serious, it is not too much to say that the world is now in a war with energy and environment. Particularly, in order to go along with streams of an international environmental regulation (Kyoto Protocol) which is strengthened daily due to a higher oil price, it is inevitable now to hurry up the development of an alternative fuel.

In order to overcome the above problems, approaches to develop alternative fuels with a high fuel efficiency using bioethanol and the like have been continually made, but there was still a need to resolve the problems such as an excessive quantity of fuel consumption. Also, there was a need to develop a high performance alternative fuel which can prevent a phase separation phenomenon of water present in a small amount in the fuel.

DETAILED DESCRIPTION Technical Problem

The present invention has been made to resolve the above mentioned problems occurring in the prior arts, and it is an object of the present invention to provide a fuel composition in which a fuel oil for internal combustion engines does not occur a phase separation phenomenon of water present in a small amount in the fuel during long-term storage and each components are fully mixed, thereby having less knock occurrence and more increased combustion efficiency. Also, it is another object of the present invention to provide a novel fuel composition containing biobutanol, having enhanced octane number, lowered harmful exhaust gas and thereby reduced environmental pollutants.

Technical Solution

In order to achieve the above objects, the fuel composition for internal combustion engines containing biobutanol according to the present invention comprises a) 1˜88% by weight of biobutanol or a mixture of biobutanol and butanol, b) 3˜75% by weight of paraffinic hydrocarbon solvents, c) 3˜35% by weight of toluene and d) 6˜30% by weight of xylene, based on the total weight of the composition.

In the present invention, the above fuel composition further comprises one or more additive selected from the group consisting of e) 1˜20% by weight of butane derivatives, f) 1˜30% by weight of pentane derivatives, g) 1˜40% by weight of hexane derivatives, h) 1˜45% by weight of benzene derivatives and i) 1˜20% by weight of heptane derivatives.

The above component b) used herein comprises paraffinic hydrocarbon or paraffinic hydrocarbon solvents having 4 to 28 carbon atoms or a mixture thereof.

Further, the fuel composition of the present invention may further comprise one or more additive selected from the group consisting of 1˜85% by weight of aliphatic alkane and alicyclic alkane having 5 to 40 carbon atoms, 0.01˜85% by weight of biodiesel, 1˜43% by weight of kerosens, 1˜32% by weight of Hi-sene, 1˜36% by weight of Hi-nine, 0.1˜5% by weight of lubricant base oil, 1˜9% by weight of butyl cellosolve, 1˜11% by weight of ethyl cellosolve, 1˜13% by weight of isopropanol, 1˜12% by weight of isobutanol and 1˜19% by weight of aromatic hydrocarbon mixture.

Further, methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE) and the like are conventionally used as an octane number enhancer. However, according to the present invention, biobutanol itself serves to increase an octane number and thus, there is no need to use a separate octane number enhancer.

When using bioethanol, there is a disadvantage that bioethanol may allow to incorporate a moisture in air, thereby resulting in a phase separation phenomenon and a corrosion in transportation pipe. As such, there is need to use a corrosion inhibitor. However, the present invention has an advantage that it is not necessary to use a separate corrosion inhibitor.

Additionally, the alternative fuel for internal combustion engines according to the present invention may comprise the above fuel composition alone or in a mixture with a fuel for internal combustion engines or an alcohol fuel.

Effect of Invention

The fuel composition for internal combustion engines according to the present invention can, when used as a fuel for internal combustion engines, significantly reduce the production and discharge of air pollutants from environment aspects, as compared with a conventional gasoline fuel. Also, the fuel composition of the present invention has increased cold-start up property and power performance as well as reduced noise generation in terms of energy efficiency, as compared with a conventional fuel for internal combustion engines.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention relates to a fuel composition for internal combustion engines, and also relates to an alternative fuel which comprises 1˜88% by weight of biobutanol or a mixture of biobutanol and butanol, 3˜75% by weight of paraffinic hydrocarbon solvents having 4˜28 carbon atoms, 3˜35% by weight of toluene and 6˜30% by weight of xylene, based on the total weight of the composition.

In the present invention, a composition ratio is based on the total weight of the composition, unless described otherwise.

Also, the present invention provides a fuel composition which further comprises, as a phase separation inhibitor, one or more component selected from the group consisting of 1˜9% weight of butyl cellosolve, 1˜11% by weight of ethyl cellosolve or a mixture thereof, based on the total weight of the composition. Furthermore, the fuel composition of the present invention may further comprise 1˜13% by weight of isopropanol, 1˜12% by weight of isobutanol, 0.001˜6% by weight of rosin, rosin derivatives, rosin acid compound or a mixture thereof, based on the total weight of the composition. Optionally, the fuel composition for internal combustion engines according to the present invention may further comprise 1˜19% by weight of aromatic hydrocarbon mixture.

The above fuel composition for internal combustion engines further comprises, more preferably, 15˜60% by weight of biobutanol or a mixture of biobutanol and butanol; 20˜50% by weight of a mixture of paraffinic hydrocarbons having 4˜28 carbon atoms; 5˜19% by weight of toluene; 6˜18% by weight of xylen; one or more phase separation inhibitor selected from 2˜5% weight of butyl cellosolve, 0.5˜6% by weight of ethyl cellosolve or a mixture thereof; 0.5˜2% by weight of rosin, rosin derivatives, and rosin acid or a mixture thereof; and 3˜12% by weight of aromatic hydrocarbon mixture, based on the total weight of the composition.

If necessary, the fuel composition of the present invention may further comprise one or more component selected from 2˜6% by weight of isopropanol and 2˜7% by weight of isobutanol, based on the total weight of the composition, thereby maximizing the phase separation inhibition effect.

In other aspect, the present invention provides a fuel composition for internal combustion engines which further comprises one or more component selected from the group consisting of 0.01˜85% by weight of biodiesel or a known diesel or a mixture thereof, 1˜43% by weight of kerosene, 1˜32% by weight of Hi-sene, 1˜36% by weigh of Hi-nine, and 0.1˜5% by weight of lubricant base oil.

In the individual aspects of the invention as mentioned above, the fuel composition may comprise, independently, one or more component selected from 1˜20% by weight of butane derivatives, 1˜30% by weight of pentane derivatives, 1˜40% by weight of hexane derivatives, 1˜45% by weight of benzene derivatives, and 1˜20% by weight of heptane derivatives. It is apparent to a person skilled in the art that, in the present invention, the butane derivatives, the pentane derivatives, the hexane derivatives, the benzene derivatives and the heptane derivatives refer collectively to the derivatives and/or isomers thereof, respectively. Therefore, further detailed description is omitted, but respective components used in the present invention will be described in detail below.

For example, the benzene derivative refers to benzene and one or more benzene derivatives selected from solvents in which hydrogen radical of benzene is substituted by one through three C1-C3 alky groups, and includes toluene, xylene, benzene, ethylbenzene, 1-methyl-3-ethylbenzene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, 1-ethyl-2,4-dimethylbenzene, indane, 1-methyl-3-propylbenzene and the like. And the butane, pentane, hexane and heptane derivatives refer collectively to compounds belonging to isomers and derivatives thereof. Here, benzene may be used, but it is preferable to not use the same in order to prevent an environment pollution.

Furthermore, the lubricant base oil may be used in the fuel composition of the present invention. The lubricant base oil includes a paraffinic base oil (content of the base oil: 45˜70%), a naphthenic base oil (content of the base oil: 65˜75%), an aromatic base oil (content of the base oil: 20˜25%) and the like. Specifically, examples thereof include one or more selected from engine oil, general industrial oil, electric insulating oil, refrigeration oil, process oil and the like. When two objects are in contact with each other and one object relatively moves against the other object, resistance that prevents the movement is called as friction. The lubricant base oil may be used to reduce the friction force or eliminate heat generated by the friction. When the lubricant base oil is used in an amount of 0.1˜5% by weight range, it is helpful to increase the fuel efficiency and reduce the heat due to the friction.

If necessary, the rosin, rosin derivative and rosin acid compound may be used in the fuel composition of the present invention. The rosin acid used herein refers collectively to organic acids contained in the rosin which can be obtained by distilling a fine resin. Rosin acid is a natural resin acid obtained by distilling a fine resin. The resin acid is a valuable resource which can hardly obtain from natural substances other than trees. From old times, fine resin has been used for the purpose of painting vessels or ships to prevent corrosion and of preventing slipping on strings of a stringed instrument. However, in most cases, the fine resin is modified for various uses. The chemical structures of resin acids comprise chemically active double bonds.

Those double bonds raise reactions between the molecules of the same resin acid or between the resin acid and other compounds (for example, maleic acid) to produce so-called polymerized Rosin. Since the double bonds result in instability when the resin acid is left in air, hydrogen is added to stabilize the resin acid. This is called as hydrogenated rosin, and used for preparing synthetic resin, ink or the like.

The rosin acid refers collectively to organic acids obtained from distillation of a fine resin, and includes abietic acid, neoabietic acid, levopimaric acid, hydroabietic acid, pimaric acid, dextonic acid, palustric acid, or the like. When the rosin acid is in the amount of 0.5˜2% by weight, it is effective in preventing corrosion.

Biobutanol used as the component a) of the present invention is produced from biomass. When using the above alcohol component, it has excellent miscibility with water and thus the phase separation does not occur. Therefore, it is very advantageous that the fuel composition of the present invention has good fuel efficiency and anti-knocking property without addition of separate phase separation inhibitor. Biobutanol serves to provide a high octane number and a high compression ratio for the fuel composition of the present invention. It also serves to prevent a phase separation and achieve a high combustion efficiency. Further, biobutanol has low vapor pressure and thus it can be used in a large quantity. Particularly, biobutanol has high density, a cold start-up property is excellent. The content of biobutanol may range from 1˜88% by weight and preferably 2˜70% by weight based on the total weight of the composition. If the content is less than the range, it is impossible to obtain sufficient effect of increase in the octane number and sufficient compression ratio. Meanwhile, if the content exceeds the range, fuel consumption is increased.

The component b) used in the present invention may include paraffinic hydrocarbon, paraffinic hydrocarbon solvent or a mixture thereof.

More specifically, the fuel composition for internal combustion engines is characterized in that the component b) includes C4˜C28 paraffinic hydrocarbon, paraffinic hydrocarbon solvent or a mixture thereof mixed with small amount of cycloparaffinic hydrocarbon or the like, which are liquids at room temperature.

Examples thereof include benzine, rubber gasoline, solvent naphtha, mineral spirits, cleaning solvent, Stoddard solvent and aromatic solvent. Trivial names thereof include canadol, isoparaffin hydrocarbon, ligroin, naphtha ligroin, refined solvent naphtha, VM&P naphtha, vanish marker's naphtha, naphtha Stoddard solvent, white spirits, Stoddard solvent naphtha, Stoddard solvent organic solvent, enamel thinner, mineral thinner, rubber solvent(naphtha), Vasol, hydrotreated light straight run(petroleum), naphtha(petroleum), hydrotreated light naphtha or the like. Brand name thereof conventionally used all over the world include 1520 Naphtha and Exxol Hexane Fluid available from ExxonMobil; Techsol-S and kixxsol available from GS-Caltex; and SBP1 (Special Boiling Point), SBP4 (Special Boiling Point), Solvent-1 and Solvent-5 (cleaning solvent) available from SK. When they are used in the content of 3˜75% by weight and preferably 20˜50% by weight, it is possible to obtain most appropriately the desired effect, to prevent clog of a nozzle attached to the internal combustion engines due to impurities, and to improve the soot preventing effect.

In the present invention, toluene or xylene may be further added in order to more improve explosive force or fuel efficiency of an engine. When using toluene in the range of 3˜35% by weight and preferably 10˜30% by weight and xylene in the range of 6˜30% by weight based on the total weight of the composition, it is possible to sufficiently improve the explosive force and fuel efficiency of the engine without generation of soot and smoke due to incomplete combustion. The xylene component refers generally to xylene isomer alone or a mixture thereof.

In the present invention, the phase separation inhibitor is a component which prevents generation of moisture during long-term storage of the fuel and condensation of water in the fuel vessel at the time of injecting the fuel into an automobile; or which prevents separation of some water incorporated from other components to cause knocking at the time of fuel combustion in engine, or lowering the fuel efficiency. In the present invention, one or more component selected from 1˜9% by weight of butyl cellosolve, 1˜11% by weight of ethyl cellosolve or the like may be used. Additionally, one or more component selected from 1˜13% by weight of isopropanol, or 1˜12% by weight of isobutanol may be used. Such phase separation inhibitor is preferably used to lengthen the life of engines. More preferably, when using one or more component selected from butyl cellosolve, ethyl cellosolve or a mixture thereof, it serves as the more excellent phase separation inhibitor.

The isopropanol serves to increase physical miscibility between the compositions by reducing interfacial tension between hydrophilic ethanol as a main fuel source in the present invention and hydrophobic aromatic compounds. The isopropanol may be used in an amount of 1˜13% by weight based on the total weight of the composition.

The butanol may include isomers thereof, e.g. normal butanol, isobutanol, secondary butanol, tertiary butanol and the like. Biobutanol using biomass as an alternative fuel to petroleum is economical in an aspect of securing the raw material since the biobutanol uses wood based raw material which occupies 97% of total vegetable biomass, and is excellent as a transportation fuel since the biobutanol has excellent property as an alternative fuel to gasoline as compared with bioethanol.

Although the biobutanol stated to be produced using microbial fermentation from early 1990s, it went into decline as the petrochemical industry was rapidly developed at 1950s. Recently, as an age of high oil prices is fixed, biobutanol is again emerged as a next generation fuel that can substitute petroleum.

The butanol can be more easily stored and transported as compared with existing bio-fuel using ethanol, and still has high thermal efficiency. The reason that the butanol has more advantage than the ethanol is because of its chemical structure. The ethanol is difficult to be stored and has a critical disadvantage of corroding a transportation pipe. Unlike this, butanol can utilize an existing infrastructure such as a crude oil transportation pipe without installation of additional equipment.

In the fuel composition for internal combustion engines, butanol contains, as a main component, biobutanol derived from biomass. Particularly, since butanol has a lower vapor pressure than ethanol, butanol can be mixed in a higher ratio than ethanol. Also, butanol has low volatility and extremely low discharge amount of soot and smoke.

Butanol can improve the cold start-up property that is a disadvantage of ethanol, and can reduce excessive fuel consumption that is, particularly, a disadvantage of alcohols. Also, since butanol has high thermal efficiency, it has excellent effect to enhance fuel efficiency and reduce exhaust gas. Further, butanol has excellent effect of preventing the phase separation even though moisture exists in the fuel. Butanol is particularly advantageous as a fuel for internal combustion engines when using in the range of 1˜88% by weight.

Isobutanol can improve the cold start-up property that is a disadvantage of ethanol and reduce excessive fuel consumption that is, particularly, a disadvantage of alcohols. Also, isobutanol has excellent effect to enhance fuel efficiency and reduce exhaust gas. Isobutanol is particularly advantageous as a fuel for internal combustion engine when using in the range of 1˜12% by weight.

Further, the fuel composition of the present invention may further comprise aromatic hydrocarbon mixture in order to increase the fuel efficiency

Examples of the aromatic hydrocarbon mixture include Aromatic-100 (available from ExxonMobil), consisting of two or more components selected from ethylbenzene, 1-methyl-3-ethylbenzene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, isopropylbenzene, propylbenzene, cumene, 1-ethyl-2-methyl benzene, 1-ethyl-2,4-dimethyl benzene, naphthalene, naphthalene derivatives, indane and indane derivatives.

Specific examples thereof include those commercially available in the common name of Aromatic-100 (from ExxonMobil), Hi-Sol 10 (from Ashland Inc), Kocosol-100 or Kocosol-150 (from SK), Techsol-100 (from GS-Caltex), polyethylbenzine, Heavy Aromatic Naphtha, High flash Aromatic, Shellsol R and the like. In particular, the aromatic hydrocarbon mixture is used to improve ignitability and fuel efficiency. When using in the content of 1˜19% by weight, desired effect of improvement in fuel efficiency can be obtained.

Furthermore, methanol can be obtained from petroleum or coal, but it can also be obtained from natural tree or the like. As such, methanol has an advantage that it can be used as an alternative fuel to petroleum.

The fuel composition for internal combustion engines according to the present invention reduces discharge of air pollutants, and, particularly when using an alcohol component like biobutanol, exhibits the effects of preventing a phase separation, enhancing an octane number and preventing an incomplete combustion, thereby enhancing the fuel efficiency. Also, the present fuel composition is a novel bio-fuel for internal combustion engines that can reduce the exhaust gas and solve the problem of environmental pollution, e.g. ground water contamination and soil pollutions that are becoming a global problem, and replace the octane number enhancer (typically, MTBE). Thus, another aspect of the present invention is related to a process for reducing the waste discharge of internal combustion engines and a novel octane number enhancer. The fuel composition for internal combustion engines according to the present invention may be used alone or in a mixture with a known conventional fuel for internal combustion engines.

In another example of the present invention, bio-diesel may be added to individual embodiment of the invention in the content of 0.01˜85% by weight based on the total weight of the composition. Conventionally, bio-diesel is mainly used in a diesel engine. However, when the bio-diesel is used in a small amount in a gasoline engine, it facilitates lubrication action, thereby giving more excellent effects of enhancing fuel efficiency and increasing the lifetime of engine, when compared with the existing case using gasoline alone. In contrast, when the content of the bio-diesel is excessive, it is disadvantageous since the bio-diesel is agglomerated to cause the clog of the oil filter of a vehicle, lowering in staring-up performance and reduction in engine power. However, in case of diesel engine, the bio-diesel may be used within the above range since the power is generated due to compressive explosion.

In addition, the fuel composition of the present invention may further include, if necessary, one or more component selected from 1˜43% by weight of kerosene, 1˜32% by weight of Hi-sene (Transient fuel oil No. 1 produced by Samsung Total Petrochemicals Co., Ltd.) and 1˜36% by weight of Hi-nine (Transient fuel oil No. 2 produced by Samsung Total Petrochemicals Co., Ltd.) Hi-sene is a by-product generated during the course of producing a petrochemical product from naphtha and the condensate as raw materials in a petrochemical plant. Hi-sene comprises heavy components having about 9˜18 carbon atoms. It is registered as Transient fuel oil No. 1 on the basis of the Petroleum and Alternative Fuel Business Act according to Korean Standards (KS), and is commonly referred to as hi-sene in the relevant field.

Hi-nine (C9+) is also a by-product generated during the course of producing a petrochemical product from naphtha as a raw material in a petrochemical plant, which is registered as Transient fuel oil No. 2. Hi-sene and Hi-nine are advantageous in that they are by-products but utilized as an alternative fuel for internal combustion engines. Particularly, Hi-nine have the flow point of −50° C. and thus can be used without changing temperature especially in winter. Further, Hi-nine contains a small amount of sulfur component, and a little sulfur oxides (SOx) is contained in the exhaust gas upon combustion. Hi-sene and Hi-none are those having significantly reduced sulfur when compared with the light oil and thus are very advantageous as the alternative fuel for internal combustion engines.

According to the present invention, aliphatic alkane or alicyclic alkane having 5˜40 carbon atoms and preferably 6˜26 carbon atoms can be further added in an amount of 1˜85% by weight, if necessary. More specifically, the fuel composition for internal combustion engines includes the component essentially consisting of C5˜C40 alkanes, derivatives of such alkanes having C1˜C2 alkane side chain and derivatives of C5˜C6 cyclic compound wherein hydrogen is substituted by C1˜C2 alkane.

Moreover, the fuel composition for internal combustion engines according to the present invention can be used as an alternative fuel or an additive for gasoline and diesel oil. When used as an additive, the fuel composition of the present invention provides excellent effects in terms of fuel efficiency, power performance, exhaust gas and noise when compared with a conventional gasoline, regardless of the amount of its addition among the total 100% by weight of gasoline.

Evaluation for the fuel composition for internal combustion engines according to the present invention was conducted according to the European evaluation method (ECE15+EUDC) which is identical with the method described in Korean Patent Registration No. 10-0525362. Unleaded gasoline of octane number #93 was used for comparison. Fuel compositions of Examples 1 to 6 of the present invention that will be described below were used. Herein, an automobile of JETTA FV7160Cix available from VOLKSVAGEN equipped with an ATK engine was used. Evaluation and analysis were then conducted according to the Measurement methods, GB18352.2˜2001 (Method for measuring exhaust gas upon driving), GB/T3845˜93 (Method for measuring exhaust gas upon starting-up), GB/T12543˜90 (Method for measuring power performance of an automobile), and GB1495-2002 (Method for measuring external noise of the automobile at the time of high-speed driving). That is, after injection of the fuel and driving the automobile to a distance of 200 km, exhaust gas upon idling (twice), exhaust gas during driving (once), fuel economy (once), power performance (once) and noise (once) were measured.

TABLE 1 Specification of the vehicle for test Model of vehicle JETTA Manufacturer of FAW-VW FV7160Cix vehicle Weight of 1130 Running distance 89.787 km vehicle Gear 5-speed Engine displacement 1.6 l Model of ATK Pressure of tire 225 kPa engine

TABLE 2 Experimental instruments and devices for test Name of device or No. instrument Model Manufacturer 1 Direct current CTDY-1211 HORIBA, Japan chassis measuring device 2 Constant volume CVS 9100 HORIBA, Japan sampling system 3 System for MEXA 9400 HORIBA, Japan analyzing exhaust of a vehicle 4 Portable device MEXA 554GE HORIBA, Japan for analyzing exhaust gas of a vehicle 5 Ignition timing 4165 Model US device 6 Non-contact LC 5100 ONO SOKKI, Japan speedmeter 7 Grader HS-5670 National Manufacturer of Instruments in Hong Seong 8 Grade correction HS-6080 National device Manufacturer of Instruments in Hong Seong 9 Table of SE-1520 ONO, Japan revolution speed 10 Thermometer SY Convection ONO Manufacturer, Japan 11 Table of DEM5-1 Manufacturer of direction and Instruments in velocity of Chang Chun wind by a magnetic sensor

The results evaluated from component analysis of gasoline and the fuel composition according to the present invention by Korean Institute of Petroleum Quality on the basis of standards for quality of gasoline, are shown in Table 3:

TABLE 3 Analysis Quality standard of results of gasoline gasoline Analysis High (regular results of Test item Regular grade gasoline) Example 1 Octane 91~94 More 92.9 99.6 number than 94 (Research Method) Distillation Temperature Lower 48.1 properties of 10% efflux than 70 (° C.) Temperature Lower 82.5 of 50% efflux than 125 Temperature Lower 154.7 of 90% efflux than 175 End point Lower 202.8 than 225 Residue Lower 1.0 (volume %) than 2.0 Water and Lower Less Less precipitate than 0.01 than 0.005 than 0.002 (volume %) Copper plate Lower 1 0.4 corrosion than 1 (50° C., 3 h) Vapor 44~96 72.6 69 pressure (37.8° C., kpa) Oxidation More More More stability (min) than 480 than 480 than 480 Residual gum Lower Less Less after washing than 5 than 1 than 1 (mg/100 ml) Sulfur powder Lower 13 Less (mg/kg) than 50 than 0.005 Pb content Lower Less Less (g/l) than 0.013 than 0.001 than 0.001 P content Lower Less Less (g/l) than 0.0013 than 0.0001 than 0.0001 Total Lower 16.29 14.7 aromatic than 30 (volume %) Benzene Lower 0.96 Not (volume %) than 1 detected Olefin Lower 14.8 1.0 (volume %) than 18 Oxygen Lower 1.53 2.26 content than 0.5~2.3 (weight %) Methanol Lower Less Not content than 0.1 than 0.01 detected (weight %)

Particularly, the result of component analysis by Korea Institute of Petroleum Quality has shown that the fuel composition of the present invention had high octane number (99.6) without separately adding an octane number enhancer. Particularly, the sulfur content was significantly reduced, while benzene that is critically harmful to human body was not detected. This can be another advantage of the present invention.

Individual components were mixed together according to the compositions described below to prepare fuel compositions for internal combustion engines according to the present invention. Evaluation for the fuel composition was conducted according to the European evaluation method (ECE15+EUDC) which is identical with the method described in Korean Patent Registration No. 10-0525362. The results are listed in Table below.

MODE FOR CARRYING OUT THE INVENTION Examples 1 to 6 and Comparative Examples 1 to 2 Example 1

1) 40% by weight of bio-butanol;

2) 40% by weight of paraffinic hydrocarbon solvent (Solvent No. 1, produced by SK) and 5% by weight of paraffinic hydrocarbon solvent (Solvent No. 5, produced by SK);

3) 7% by weight of toluene; and

4) 8% by weight of xylene

Using a mixed fuel prepared by mixing with the above fuel composition, evaluations of performance were conducted according to the European Evaluation Method (ECE15+EUDC). The results are listed in Tables below.

Example 2

1) 42% by weight of bio-butanol;

2) 35% by weight of hydrocarbon solvent (Solvent No. 1) and 7% by weight of hydrocarbon solvent (Solvent No. 5);

3) 9% by weight of toluene;

4) 2% by weight of aromatic hydrocarbon mixture, Techsol-100 (available from GS Caltex);

5) 2% by weight of isopropanol;

6) 2% by weight of Hi-nine; and

7) 1% by weight of butyl cellosolve.

A mixed fuel was prepared by mixing 10% by weight of the above fuel composition with 90% by weight of 93# unleaded gasoline. Evaluations of performance were then conducted according to the European Evaluation Method (ECE15+EUDC). The results are listed in Tables below.

Example 3

1) 40% by weight of bio-butanol;

2) 40% by weight of paraffinic hydrocarbon solvent (Solvent No. 1, produced by SK) and 5% by weight of paraffinic hydrocarbon solvent (Solvent No. 5, produced by SK);

3) 7% by weight of toluene; and

4) 8% by weight of xylene

A mixed fuel was prepared by mixing 40% by weight of the above fuel composition with 60% by weight of 93# unleaded gasoline. Evaluations of performance were then conducted according to the European Evaluation Method (ECE15+EUDC). The results are listed in Tables below.

Example 4

1) 43% by weight of bio-butanol;

2) 35% by weight of paraffinic hydrocarbon solvent (Solvent No. 1) and 4% by weight of hydrocarbon solvent (Solvent No. 5);

3) 11% by weight of xylene;

4) 2% by weight of aromatic hydrocarbon mixture, Techsol-100 (available from GS Caltex);

5) 2% by weight of isopropanol;

6) 2% by weight of Hi-nine; and

7) 1% by weight of butyl cellosolve.

Using the above fuel composition, evaluations of performance were conducted according to the European Evaluation Method (ECE15+EUDC). The results are listed in Tables below.

Example 5

1) 42% by weight of bio-butanol;

2) 35% by weight of hydrocarbon solvent (Solvent No. 1) and 5% by weight of hydrocarbon solvent (Solvent No. 5);

3) 10% by weight of toluene;

4) 2% by weight of aromatic hydrocarbon mixture, Techsol-100 (available from GS Caltex);

5) 2% by weight of isopropanol;

5) 2% by weight of Hi-sene; and

7) 2% by weight of butyl cellosolve.

Using the above fuel composition, evaluations of performance were conducted according to the European Evaluation Method (ECE15+EUDC). The results are listed in Tables below.

Example 6

1) 40% by weight of bio-butanol;

2) 40% by weight of paraffinic hydrocarbon solvent (Solvent No. 1, produced by SK) and 4.5% by weight of paraffinic hydrocarbon solvent (Solvent No. 5, produced by SK);

3) 7% by weight of toluene;

4) 8% by weight of xylene; and

5) 0.5% by weight of biodiesel

Using a mixed fuel prepared by mixing with the above fuel composition, evaluations of performance were conducted according to the European Evaluation Method (ECE15+EUDC). The results are listed in Tables below.

As a result, it has been shown that the effect of lowering exhaust gas discharge and the fuel efficient were noticeable.

Comparative Example 1

1) 100% by weight of 93# unleaded gasoline

Using the above gasoline, evaluations of performance were conducted according to the European Evaluation Method (ECE15+EUDC). The results are listed in Tables below.

Comparative Example 2

1) 36% by weight of hydrocarbon solvent (Solvent No. 1) and 6% by weight of hydrocarbon solvent (Solvent No. 5);

2) 10 by weight of toluene;

3) 2% by weight of aromatic hydrocarbon mixture, Techsol-100 (available from GS Caltex);

4) 40% by weight of 93# unleaded gasoline;

5) 2% by weight of isopropanol;

6) 2% by weight of Hi-nine; and

7) 2% by weight of butyl cellosolve.

Using the above fuel composition, evaluations of performance were conducted according to the European Evaluation Method (ECE15+EUDC). The results are listed in Tables below.

TABLE 4 Test Results of exhaust gas during idling of JETTA(VOLKSVAGEN) automobile Test items Idling speed CO(%) HC(ppm) Example 1 800 0.00 <20 Example 2 800 0.00 <20 Example 3 800 0.00 <20 Example 4 800 0.00 <20 Example 5 800 0.00 <20 Example 6 800 0.00 <20 Example 7 800 0.00 <20 Comparative 800 0.00 <20 Example 1 Comparative 800 0.00 <20 Example 1

The result of the exhaust gas measurement according to the method of GB18352.2-2001 has shown that no increase of exhaust gas was found after driving 200 km as compared with the exhaust gas at the time of idling. Thus, there was no pollution in exhaust gas at the time of idling, for all cases.

TABLE 5 Test Results of discharge of pollutant and economical efficiency of fuel in JETTA(VOLKSVAGEN) automobile Fuel consumption Test items HC(g/km) CO(g/km) NOX(g/km) (l/km) Example 1 0.01 0.39 0.06 7.68 Example 2 0.05 0.60 0.16 8.00 Example 3 0.05 0.54 0.14 7.98 Example 4 0.04 0.45 0.09 7.74 Example 5 0.03 0.44 0.08 7.75 Example 6 0.02 0.40 0.06 7.70 Comparative 0.11 0.88 0.28 8.16 Example 1 Comparative 0.08 0.70 0.19 8.08 Example 1

As can be seen from the above Table, the effects of the lowering of pollutants and the fuel efficiency were noticeable in case of the composition of Example 1 (containing biobutanol, paraffinic hydrocarbon solvent, toluene and xylene) as compared with that of Comparative Example 1 (unleaded gasoline).

Also, the effects of the lowering of pollutants and the fuel efficiency were noticeable in case of the composition of Example 6 (containing biobutanol, paraffinic hydrocarbon solvent, toluene, xylene and biodiesel) as compared with that of Comparative Example 1 (unleaded gasoline).

TABLE 6 Test Results of power performance of JETTA(VOLKSVAGEN) automobile (unit: sec) Duration of Duration of acceleration acceleration to Test items to 5th speed 4th speed Example 1 21.87 19.54 Example 2 24.77 21.92 Example 3 24.66 21.91 Example 4 22.07 20.07 Example 5 22.16 20.08 Example 6 21.79 19.66 Comparative 25.98 23.00 Example 1 Comparative 25.20 22.24 Example 1

As can be seen from the above Table, the times required for acceleration to the 4th or 5th speed after driving the distance of 200 km, when using the composition of Example 6 (containing biobutanol, paraffinic hydrocarbon solvent, toluene, xylene and biodiesel) were much faster acceleration force than that required in case of using common #93 unleaded gasoline of Comparative Example 1.

The results of measurements of noise at accelerated driving of JETTA (VOLKSVAGEN) automobile are shown in Tables 7-1 to 7˜7 below.

TABLE 7-1 Test results after driving 200 km in Comparative Example 1 L/R Engine Engine mean Loca- revolution revolution value Medium Maximum Speed tion rate rate (each) value value 2nd Left 3800 4100 73.4 73.5 73.9 Speed Right 3800 4100 73.6 3nd Left 2800 3050 73.9 74.3 Speed Right 2500 3050 74.6 Background noise 54.6

TABLE 7-2 Test results after driving 200 km in Example 1 L/R Engine Engine mean Me- revolution revolution value dium Maximum Speed Location rate rate (each) value value 2nd Left 3800 4100 71.8 71.3 70.7 Speed Right 3800 4100 70.7 3nd Left 2800 3050 70.0 70.0 Speed Right 2800 3050 70.0 Background noise 54.3

TABLE 7-3 Test results after driving 200 km in Example 2 L/R Engine Engine mean Me- revolution revolution value dium Maximum Speed Location rate rate (each) value value 2nd Left 3800 4100 73.7 73.4 73.0 Speed Right 3800 4100 73.1 3nd Left 2800 3050 72.5 72.6 Speed Right 2800 3050 72.6 Background noise 54.4

TABLE 7-4 Test results after driving 200 km in Example 3 L/R Engine Engine mean Me- revolution revolution value dium Maximum Speed Location rate rate (each) value value 2nd Left 3800 4100 72.9 72.3 72.4 Speed Right 3800 4100 71.7 3nd Left 2800 3050 72.3 72.5 Speed Right 2800 3050 72.7 Background noise 54.3

TABLE 7-5 Test results after driving 200 km in Example 4 L/R Engine Engine mean Me- revolution revolution value dium Maximum Speed Location rate rate (each) value value 2nd Left 3800 4100 72.5 72.0 72.3 Speed Right 3800 4100 71.4 3nd Left 2800 3050 72.6 72.5 Speed Right 2800 3050 72.4 Background noise 54.4

TABLE 7-6 Test results after driving 200 km in Example 5 L/R Engine Engine mean Me- revolution revolution value dium Maximum Speed Location rate rate (each) value value 2nd Left 3800 4100 74.5 73.4 72.4 Speed Right 3800 4100 72.6 3nd Left 2800 3050 71.3 71.3 Speed Right 2800 3050 71.2 Background noise 54.6

TABLE 7-7 Test results after driving 200 km in Example 6 L/R Engine Engine mean Me- revolution revolution value dium Maximum Speed Location rate rate (each) value value 2nd Left 3800 4100 72.0 72.0 71.6 Speed Right 3800 4100 72.0 3nd Left 2800 3050 71.3 71.1 Speed Right 2800 3050 70.9 Background noise 54.6

As can be seen from the result of noise measurement, the fuel composition according to the present invention exhibited excellent effect of reducing noise on the whole.

Although the preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 

1. A fuel composition for internal combustion engines comprising: a) 1˜88% by weight of biobutanol or a mixture of biobutanol and butanol, b) 3˜75% by weight of paraffinic hydrocarbon solvents, c) 3˜35% by weight of toluene, and d) 6˜30% by weight of xylene, based on the total weight of the composition.
 2. The fuel composition for internal combustion engines as set forth in claim 1, further comprising one or more component selected from the group consisting of 1˜85% by weight of aliphatic alkane and alicyclic alkane having 5 to 40 carbon atoms, 1˜43% by weight of kerosens, 1˜32% by weight of Hi-sene, 1˜36% by weight of Hi-nine, 0.1˜5% by weight of lubricant base oil, 1˜9% by weight of butyl cellosolve, 1˜11% by weight of ethyl cellosolve, 1˜13% by weight of isopropanol, 1˜12% by weight of isobutanol and 1˜19% by weight of aromatic hydrocarbon mixture, based on the total weight of the composition.
 3. The fuel composition for internal combustion engines as set forth in claim 1, further comprising 0.001˜6% by weight of rosin, rosin derivatives, and rosin acid or a mixture thereof.
 4. The fuel composition for internal combustion engines as set forth in claim 1, further comprising 0.01˜85% by weight of biodiesel.
 5. An alternative fuel for internal combustion engines, comprising the fuel composition as set forth in claim 1 alone or in a mixture with a fuel for internal combustion engines or alcohol fuel. 